The hulls are not the same.
The deal with shotshell loading is there is no "working up" of the load, you have to stick with the component's listed and the shot/powder charge each cannot vary more than 5% of the listed load.
Pressure changes happen rapidly with shot shell.
You can't change the Primer, you can't change the hull, you can't change the wad, shot charge or the powder charge, no mix matching things,,,
The Lyman Shot Shell loading manual is golden. It lists 1000's of loads and in true Lyman fashion they stick to the basic procedures and don't try to sell ya something.
You can use previuosly fire hulls, and most loading shops have used hulls for sale, I stated out buying Winchester AA hull for $8.99 a hundred, but hit the clubs clay shooting range and picked up a few hundered more just for picking through the scrap bin.
Did you just pick-up shot shell loading tools?